Hydraulically operated electric switch



July 18, 1933. J. w. WHITE HYDRAULICALLY OPERATED ELECTRIC SWITCH Filed NOV. 23, 1931 INVENTOR JairzWi/iz'ta BY WW W ATTORNEYIS Patented July 18, 1933 UNITED STATES PATENT OFFICE JOHN WILLIAM WHITE, OF DETROIT, MICHIGAN, ASSIGNOR TO KELSEY-HAYES WHEEL CORPORATION, OF DETROIT, MICHIGAN, A CORPORATION OF NEW YORK HYDRAULICALLY OPERATED ELECTRIC SWITCH Application filed November 28, 1931. Serial No. 576,897.

The invention relates to hydraulically operated electric. switches being more particularly designed'for use in the operation of stop lights in connection with hydraulically operated brakes. In the present state of the art switches of this character have been devised in which the movable contact member is actuated by the flexure of a rubber diaphragm extending across a cup shaped member which contains the operating fluid. It has been found, however, that such constructions frequently fail. due to the breaking of the diaphragm which by permitting escape of the fluid may render both the switch and the brake inoperative.

It is the object of the present invention to obtain a switch free from this defect and to this end the invention consists in the construction as hereinafter set forth.

In the drawing:

Figure 1 is a central longitudinal section through the switch in normal position;

Figure 2 is a similar view showing the circuit closing position.

My improved switch comprises an outer metallic housing A which is provided with a threaded nipple B for attachment at a suitable point in a hydraulic brake system as for instance at the end of the master cylinder. The portion A is of cup shaped form having a cylindrical portion A of one diameter and a portion A of a greater diameter with a shoulder A therebetween. There is also a thin annular metallic flange A at the outer end of the portion A. C is an insulator disk or head fitting within the portion A and retained therein by the peening over of the flange A. Between the disk C and the shoulder A is an annular washer D extending inward beyond the shoulder A and overlapping the cylindrical portion A. E is a cup formed of rubber or other suitable resilient material fitting within the portion A and provided with an integral disk shaped head E. This cup is molded to have its cylindrical flange of an external diameter slightly in excess of the internal diameter of the portion A so that when contracted and placed in such portion the inherent resiliency will cause the flange to tightly seal against the metallic casing. The cup is also formed with a rounded fillet between this cylindrical flange and the head which prevents the localization of stresses at any one point when the head is flexed under hydraulic pressure.

The insulator head C has secured thereto electric terminals F and F which extend through apertures in said head and are riveted over on their inner ends to retain the same to the head and to form slightly projecting contacts. G is a slightly dished metallic disk arranged within the annular washer D and having its convex side bearing against the head E of the cup. H is a spring engaging a central recess in the inner face of the insulator head C and bearing against the disk G to hold the same in contact with the flexible head E of the cup E.

With the construction as described, the parts are assembled by first inserting the dip E into the portion A of the casing, then placing of the washer D against the shoulder A. then placing the insulator head C against the washer D and finally peening over the flange A to retain all of the parts in this relation. When the casing is connected with a hydraulic brake system the increase in fluid pressure due to the setting of the brakes will flex the head E moving the disk H outward and into contact with the inner ends of the terminals E and E. In thus flexing the head E, no localized stre$ is developed and on account of the relatively small area of exposure to the fluid there is but slight danger of developing a destructive pressure. The inwardly projecting portion of the washer D forms an abutment for limiting any outward movement of the cup E under hydraulic pressure and the thickness of the washer D is sutlicient to normally hold the terminal contacts spaced from the disk G which forms a bridge contact therefor. Also, as the washer D is formed of comparatively rigid material it will form a solid abutment against which the head C rests when it is secured by the peening over of the flange A.

In operation, fluid pressure within the cup- E will first hold the flanges of this cup in sealing contact with the cylindrical portion A of the casing and second, will flex the head. overcoming the tension of the spring H and forcing the head E outward, carrying the dished disk G into electrical contact with the terminals F F thereby closing the electric circuit. Upon release of the fluid pressure the resiliency of the cup, together with that of the spring H, will return the parts to normal position separating the disk G from the terminals F F.

The advantages of the construction above described are first, that the cup E may'be made of smaller diameter than with construetions heretofore used, as it engages'a cylin-' drical portion of the casing that is of smaller 5 diameter than the insulator head C. This smaller diameter together with the integral connection ,between the head E and the flanges of the cup im art suflicient strength to withstand the maximum pressures devel- 1 oped in the hydraulic system. Thus one of the chief objections to constructions hereto-- fore used is overcome. Another advantage is that the flexible diaphragm is not clamped having its annular wall held in sealing contact with the wall of said casing of fluid pressure and its head forming an actuating means for said bridge contact.

2. A hydraulically operated electric switch comprisin 'a cup-like casing, an insulator head for c osing said casing, electrical terminals extending through said head and providing spaced contacts on the inner face thereof. a bridge contact member, resilient means for holding said bridge contact member normally spaced from the contacts on said head, and a cup of resilient flexible material within said cup-like casing, the annular wall of said cup being held by the fluid pressure in sealing contactwith the wall of said casing and the flexible head of said cup form ing an actuating means for said bridge contact member.

3. A hydraulically operated-electric switch comprising a cup-like casing, an insulator head for closing said casing, electrical terminals extending through said head and forming spaced contacts on the inner face thereof, a bridge contact member, resilient means for holding said bridge contact member normally spaced from the contacts on said head and a cup of resilient flexible material within said cup-like casing and held thereagainst by fluid pressure, the annular wall of said cup being of a normal diameter slightly in excess of the internal diameter of said casing to be under compression in said casing and'held thereby in initial sealing contact with the casing wall, the flexible head of said cup forming an actuating means for said bridge contact member.

4. A hydraulically operated electric switch comprising a cup like casing having the small diameter cylindrical portion and a larger wall of said cup being held in sealing contact with the casin wall by fluid pressure, and 30 the head of sa d cup abutting against said washer whereby the expansionof said head by fluid pressure therein will move said bridge contact into connection with the contacts on said insulator head.

5. A hydraulically operating electric switch comprisin a cup-like casing, an insulator head for c osing said casing, electrical terminals extending through said head and forming spaced contacts on the inner face thereof, a cup of flexible resilient material within said cup-like casing having-its annular wall in sealing contact with the wall of said casing, an annular spacer for holding'said flexible cup spaced from said insulator head, a bridge contact member within said annular spacer adjacent to the head of said flexible cup, a spring centrally engaging said bridge contact member and a recessed abutment in said insulator head to hold said bridge contact normally spaced from the contacts on said insulator head whereby fluid pressure within the cup will flex the head thereof and move said bridge contact into electrical connection with the contacts on the insulator head.

6. A hydraulically operated electric switch comprising a cylindrical casing, an insulator head therefor, electrical terminals extending through said head and forming 110 spaced contacts on the inner face thereof, a bridge contact member, a flexible diaphragm extending across said casing adjacent to said bridge contact member and means for sealing said diaphragm to said casing by hydraulic 1 pressure.

7. A hydraulically operated electric switch 1 comprising a cylindrical casing, an insulator head for closing the same, electrical terminals extending through said head and forming spaced contacts on the inner face thereof, a bridge contact member and a flexible diaphragm extending across said casing adjacent to said bridge contact member and provided with a cylindrical flange whereby hydraulic pressure applied linearly and radially of said diaphragm will seal the same to said casing and operate said bridge contact member.

JOHN WILLIAM WHITE. 

